1. Field of the Invention
The invention relates to a thickness planing apparatus. More particularly, this invention relates to a thickness planer having a carriage locking mechanism to minimize vibration and movement of the carriage during the planing operation. This invention includes a depth of cut indicator to display the thickness of the wood to be removed during the planing operation. This invention further includes a mechanism for facilitating setting the carriage and cutting head to a predetermined height over the to base, quickly and accurately for planing a workpiece to predetermined thicknesses.
2. Description of the Related Art
Planing a workpiece is a common operation in the field of woodworking. Planing is the removal of wood from a surface or face of a board so as to make it flat, uniform, and smooth.
It is generally known that a typical thickness planer is comprised of a base upon which support columns are perpendicularly mounted. Supported by the support columns is a carriage that houses a rotating cutting head. The cutting head has at least one cutting knife which, when rotated, removes material from the workpiece passing through the planer.
A lead screw is generally provided to adjust the height of the carriage above the base. Since the cutting head is rotatably attached to the carriage, the height of the carriage determines the thickness of the workpiece exiting the planer. The difference between the thickness of the workpiece entering the planer and the thickness of the workpiece exiting the planer is the depth of cut. The depth of cut is the thickness of the workpiece being removed by one pass through the thickness planer.
A motor-powered infeed roller pulls the workpiece into the planer, while an outfeed roller assists the workpiece to exit the planer. Also standard components on a known thickness planer are an infeed table and an outfeed table.
To provide versatility in a commercial thickness planer, it is common for the carriage to be adjustable to different heights. However, during the cutting operation, it is preferred that the carriage be securely attached to the housing of the thickness planer. Otherwise, vibration and movement of the carriage during the planing operation may produce undesired xe2x80x9csnipexe2x80x9d or localized variations in the workpiece thickness. This undesired vibration and movement is especially prevalent when the workpiece is entering or exiting the thickness planer, i.e. at the beginning and end of a cut.
In some thickness planers, the base is stationary and the carriage moves to adjust the height of the carriage with respect to the base. In other versions of thickness planers, the carriage is stationary and the base moves to adjust the distance the base extends below the carriage.
Multiple attempts to provide carriage locks have been attempted. For example, U.S. Pat. No. 5,794,675 to Garcia discloses a locking assembly containing forks running the length of the support columns. By deflecting these long forks and sandwiching them between the carriage and the support columns, friction secures the carriage. Further, Garcia attempts to lock the carriage in line with the cutting head instead of locking the carriage at a location away from the cutting head. It has been found that the close proximity of the locking mechanism to the cutting head may not provide adequate stability when locking the carriage.
Another attempt to provide a carriage lock is disclosed in U.S. Pat. No. 5,771,949 to Welsh et al. Disclosed in this patent are various resiliently deflectable mechanisms having springs, levers, or more resiliently deflectable members to secure the carriage at a given height.
However, because of the geometries, systems of the prior art fail to produce a mechanical advantage to reduce the amount of force necessary to lock the carriage, compared to the holding strength of the locking mechanism. Further, because the systems disclosed in prior art systems rely upon resiliently deflected members, these systems over time fatigue and become less effective at securing the carriage. Further, the prior art systems utilize fixed links or rods to indicate the braking and locking action. Not only do these systems lose their effectiveness over time, but also they require maintenance of the worn, fixed links.
Thus, there is a need for a mechanism which minimizes the amount of snipe in a workpiece by minimizing the movement and vibration of the cutter head and carriage. Further, there is a need for the mechanism to require a small amount of force to lock the carriage into place, yet securely lock the carriage.
Thickness planers generally have a limit to the amount of material that should be removed in one pass, for a given type of cutting blade, motor size, etc. of a machine, and the material and the width of the workpiece. Manufacturers therefore often recommend a maximum depth of cut per planing operation. For example, a maximum depth of cut of xe2x85x9 inch may be recommended for a six-inch wide wooden workpiece processed with a thickness planer. Therefore, there is a need to determine quickly and accurately the depth of cut without having to continually stop and manually measure the workpiece.
Various attempts have been made to automatically determine the depth of cut of a workpiece entering a thickness planer. For example, U.S. Pat. No. 5,927,357 to Welsh et al. discloses a workpiece indicator portion which is resiliently displaced by the entering workpiece. The resiliently displaced portion then deflects a pointer which moves along a scale mounted on the housing.
However, with this system, the repeated deflections of the resiliently displaced workpiece-engaging portion produces inaccurate results over time. Also, as this system relies upon the bending of the workpiece-engaging portion instead of a more positive-contact arrangement, inaccuracies result. Further, by having the scale mounted on the housing instead of the carriage itself, inaccuracies may result.
Often when planing wood, it is desired to produce workpieces of standard thicknesses, such as xe2x85x9 inch, xc2xc inch, xc2xd inch, etc. It is therefore desirable to have predetermined stops provided with a thickness planer to stop the carriage at a given height, thus producing finished product of standard thickness.
Various attempts have been made to produce predetermined stops for thickness planers. For example, U.S. Pat. No. 5,927,357 to Welsh et al. discloses a depth stop having three screws of varying heights attached to a rotatable main body. A portion of the main body resides directly below the carriage while the remainder of the main body resides outside of the travel area of the carriage. The height of the pin extending from the portion of the main body residing under the carriage therefore determines the height at which the carriage stops. By rotating the main body, one of three screws of different heights will determine the height of the carriage.
However, it is difficult to quickly and accurately determine at what height the screws are set, i.e. it is not an easy task to set the carriage height to produce a xc2xe inch finished workpiece without performing a calibration process. Further, once one of the screws were set to produce the xc2xe inch finished workpiece, one twist of that screw will de-calibrate the settings, requiring an operator to repeat the calibration process.
Thus, it is desirable to produce a thickness planer which can be more quickly, more easily, and more accurately set to produce predetermined thicknesses of workpieces than is available in the prior art. For the foregoing reasons, there is a need for a carriage locking mechanism that is capable of quickly and securely fixing the carriage at a given location above the base. Further, there is a need for an accurate depth of cut indicator. Finally, there is a need for a predetermined stop apparatus to allow an operator to quickly, yet accurately, set the carriage at predetermined heights. The claimed invention is directed at overcoming, or at least minimizing, disadvantages of the prior art.
The invention relates to a thickness planer. In some embodiments, the thickness planer employs a carriage lock mechanism to securely lock the carriage, and thus the cutting head, at a given height above the base. In some embodiments, advantages such as the use of a threaded arrangement and free-floating, non-deflectable shoes, produce mechanical advantages and a secure lock superior to other mechanism currently known. This secure lock reduces carriage vibration and movement and minimizes snipe produced in a workpiece.
In other embodiments, a depth of cut indicator is provided which quickly and accurately determines the thickness of the material about to be removed in the planing operation. Because the depth of cut indicator does not have a resiliently deflectable member contacting the workpiece, this depth of cut indicator is more reliable over time than prior art systems. In some embodiments, the depth of cut indicator includes a rack and pinion arrangement to improve the accuracy of the unit: i.e. movement of the rod contacting the workpiece causes a corresponding movement of a pointer thus resulting in a more accurate reading than systems which rely on deflection. Further, the location and geometries of the depth of cut indicator provide more accurate and easy-to-read results that prior art systems.
In some embodiments, an apparatus having multiple predetermined stops for thickness planers is described. The systems is easy to use and includes a scale by which a user may utilize a given stop. Some embodiments include stops of given standard values, each stop keeping its original carriage height setting such that the apparatus will not require re-calibration because of a turn of a screw.
In some embodiments, a depth of cut indicator for use with a thickness planer is described, the thickness planer having a base and a carriage with a cutting head to remove material from a workpiece, the carriage being displaceable from said base at a defined distance by at least two support columns, the workpiece passing above a work area on the base and contacting the cutting head on the carriage to remove a layer of the workpiece, the depth of cut indicator comprising a pointer housing fixedly attached to said carriage, said pointer housing having a scale to indicate a depth of the material removed, a pointer pivotally mounted within said housing, said pointer having a pointing indicator and a spur, an elevating pointer rod movably attached to said pointer housing, said elevating pointer rod having an end to contact the workpiece and at least one ring, said ring on the elevating pointer rod being connected to the spur on said pointer such that as the carriage is lowered and the end of the elevating pointer rod contacts the workpiece, the pointer rotates to align the pointing indicator with the scale on the pointer housing to correspond to the amount of material being removed by the thickness planer. In some aspects, the pointer rod is chamfered. In some aspects, the depth of cut indicator has a coil spring.
In another embodiment of the present invention, a carriage lock is described for use with a thickness planer, the thickness planer having a base and a carriage with a cutting head to remove material from a workpiece, the carriage being displaceable from is said base at a defined distance by at least two support columns, the workpiece passing above a work area on the base and contacting the cutting head on the carriage to remove a layer of the workpiece, the carriage lock comprising at least two shoes, each shoe located in the carriage and being adjacent one of the support columns, a sleeve having a threaded end and a second end, a right plate lock having at least one foot, said right plate lock being functionally associated with the threaded end of the sleeve, a left plate lock having at least one foot, said left plate lock being mounted on the other end of the sleeve, a handle rotatably connected to said threaded end of said sleeve such that rotation of said handle causes the right plate lock to move toward the left plate lock, the feet of the right and left plate locks pressing the at least two shoes thus releasably securing the carriage to the support columns at a height over the base. In some aspects the carriage lock has at least two shoes located in slots on an outside of at least two support column collars, said at least two support column collars attached to the carriage, said at least two support columns being adapted to be received into said at least two support column collars, the rotation of said handle causing the right plate lock to move toward the left plate lock, thus applying pressure upon the at least two shoes on the outside of at least two support column collars, thus releasably securing the support column collars to the support columns to maintain the carriage at a given height over the base during the planing operation. In some aspects a method of locking a carriage of a thickness planer is described.
In other embodiments a predetermined stop mechanism is described for use with a thickness planer, the thickness planer having a base and a carriage with a cutting head, the carriage being displaceable from said base at a defined distance by at least two support columns, the workpiece passing between a work area on the base and the cutting head on the carriage to remove a layer of a workpiece, the predetermined stop mechanism comprising a step block having a first step at a first height and a second step having a second height, the step block being moveably attached to the base, and a step rod attached to the carriage, the step rod contacting the first step to set the carriage at a first predefined distance above the base, the step rod contacting the second step to set the carriage at a second predefined distance above the base. In some aspects the predetermined stop mechanism has a positive stop mechanism, sometimes being a grooved block connected to a perimeter of the base, a first trough of the grooved block releasably securing the step block such that the step rod contacts the first step to set the carriage at a first predefined distance above the base, a second trough of the grooved block releasably securing the step block such that the step rod contacts the second step to set the carriage at the second predefined distance above the base.
In some embodiments a thickness planer is described for reducing a thickness of a workpiece, comprising a base having a work area over which the workpiece travels, at least two support columns perpendicularly connected to said base, a carriage having a cutting blade assembly, the carriage being movably attached to said two support columns thus raising said carriage a distance over said base, the cutting blade assembly adapted to cut the workpiece as it passes between the work area on the base and the carriage, and a carriage lock to lock said carriage at the distance above the base, the carriage lock having at least two shoes, each shoe located in the carriage and loosely abutting one of the support columns, a sleeve having a threaded end and a second end, a right plate lock having at least one foot, said right plate lock being functionally associated with the threaded end of the sleeve, a left plate lock having at least one foot, said left plate lock being mounted on the other end of the sleeve, a handle rotatably connected to said threaded end of said sleeve such that rotation of said handle causes the right plate lock to move toward the left plate lock, the feet of the right and left plate locks pressing the at least two shoes thus releasably securing the carriage to the support columns at a height over the base.
In some aspects, the thickness planer further comprises a depth of cut indicator having, a pointer housing fixedly attached to said carriage, said pointer housing having a scale to indicate a depth of the material removed, a pointer pivotally mounted within said housing, said pointer having a pointing indicator and a spur, an elevating pointer rod movably attached to said pointer housing, said elevating pointer rod having an end to contact the workpiece and at least one ring, said ring on the elevating pointer rod being connected to the spur on said pointer such that as the carriage is lowered and the end of the elevating pointer rod contacts the workpiece, the pointer rotates to align the pointing indicator with the scale on the pointer housing to correspond to the amount of material being removed by the thickness planer. In some aspects, the thickness planer further comprises a predetermined stop mechanism having a step block having a first step at a first height and a second step having a second height, the step block being moveably attached to the base, and a step rod attached to the carriage, the step rod contacting the first step to set the carriage at a first predefined distance above the base, the step rod contacting the second step to set the carriage at a second predefined distance above the base.
In other embodiments, a carriage lock for use with a thickness planer is described, the thickness planer having a base and a carriage with a cutting head to remove material from a workpiece, the carriage being displaceable from said base at a defined distance by at least two support columns, the workpiece passing above a work area on the base and contacting the cutting head on the carriage to remove a layer of the workpiece, the carriage lock comprising at least two locking rods, each rod adapted to be received within the carriage adjacent one of the support columns, each rod having an inside end and an outside end, a double cam being adapted to be received within the carriage and being adjacent said inside ends of said at least two locking rods, and a lever to control the rotation of the cam, such that by moving the lever, the double cam is rotated to contact the inside ends of the at least two locking rods, the outside ends of said at least two locking rods contacting said support columns, securing the carriage.